Pawl and ratchet gearing



W. B. BENNLTL PAwL AND RATQHET GEARING. FILED JAN. 26, 1917.

INVENTOR Mil/21m 5 Benn/W. W

ATTORNEY Jam. 2 11923.

- W, B. BENNITT PAWL AND RATCHET GEARI NG 4 SHEETS'SHEET 2 FILED JAN. 26, 1917.

v INVENTOR Vl l/vfwm Benn/77".

WITNESSES .60! FM.

W. B. BENNITT. PAWL AND RATCHET GEARING FILED JAN. 26. 1917.

4 SHEETS'SHEET 4 WITNESSES 60 ATTORNEY 1V ILLIAll'X W'ESTIIWG IGUSE ELECTRIC it MANUFAGTURING CO'l'TPANY, A GURPOB-A E'ION PENNSYLVANIA.

PAWL AND BEIGE-IE1 GEARING.

.ltpplioation filed. January 26, 1917. Serial No. 144,654.

gearing and particularly to gearing for iniparting a rotary motion to a shaft by predetermined steps, such as, for instance, is required for operating electric-motor controllers, circular-dial switches and the like.

The object of my invention is to construct a mechanism by means of which a shaft may be rotated in one direction in steps, by means of a suitable handle, but so arranged that, between steps, the handle must be moved in the opposite direction a predetermined amount to enable the pawl to take up a fresh tooth in the ratchet and then in the forward direction through a distance greater than that through which it was moved baclo wardly, whereby the position of the handle will show through how many steps the shaft has been rotated.

Another object of the invention is to provide a double-acting structure of the type in question, whereby a shaft may be rotated in opposite directions from a given zero or datum mark.

According to the present invention, the ratchet teeth are formed on a cam-shaped plate, that is to say, each successive ratchet tooth is located nearer to the axis of rotation of the plate, than the preceding tooth and steps are provided which prevent the movement of the handle and pawl, and consequent rotation of the ratchet plate and shaft, in a forward direction beyond definite positions, which are different for each tooth of the ratchet. A. lined cam is also provided for the purpose of guiding the pawl in such manner as to cause it to engage a definite tooth of the ratchet, depending onthe position to which the ratchet has previously been moved. in cases where a double pawland-ratchet mechanism is provided for the purpose of obtaining a rotation by definite steps in either direction, the fixed cams are adapted also to prevent the engagement of the ratchet teeth with the pawl that is not being employed to rotate the ratchet.

scribed with reference to the accompanying drawings, which illustrate the improved mechanism for the purpose of rotating the shaft of an electric-motorcontroller by predetermined steps in either direction from a fixed Zero or datum position. Fig. 1 is a plan view, and Fig. Qis a view in side elevation, of the mechanism. Figs. 3 to 13 are views of various parts, as hereinafter explained.

Referring now to the drawings, the shaft 1 to be rotated has a ratchet-plate 2 firmly secured thereto that is provided with two sets of ratchet teeth numbered 3 to 6 and 7 to 10, respectively. The ratchet-plate is provided with a sleeve 11 surrounding the outer end of the shaft 1 to which it is firmly secured by a transverse pin 12. A plan view and a side view of the ratchet-plate and sleeve are shown in Figs. 3 and 1 respectively, from which it will be seen that the ratchet teeth are formed on a cam-shaped plate in such manner that each successive tooth of each set is located nearer to the axis of rotation of the plate than the preceding tooth.

A handle 13 is mounted to rotate loosely upon the sleeve 11 of the ratchet-plate and has secured to it a plate 1% (see Figs. 5 and 6) that is provided with side extensions or ears 15 and 16 to which are pivoted pawls 17 and 18 by means of pivots 19 and 20, respectively. The pawls 17 and 18 are shown in detail in Fig. 7 to F ig. 10, inclusive. The pawl 17 is provided with an extension or boss 21, and the pawl 18 with an extension or wing 22, for purposes hereinafter explained; the pawls being; respectively provided with springs 23 and 24k to cause them to engage the ratchet teeth. The handle is maintained in position on the sleeve 11 by means of a washer 25, through which eX- tends the transverse pin 12.

Attached to a fixed part of the apparatus, the cover of the controller, for example, as indicated in the drawing, are cam discs 26 and 97, the shapes of which will be clearly seen from Fig. 12 of the drawing, and surrounding the cam discs, are annular plates 28 and 29, the inner surfaces of which are provided with notches or steps 34 to 37 andto 33, respectively. The annular red! plates are alsoprovided near their outer ends, with projecting steps 38 and 39 that are adapted to engage a projection 10 on the handle to thereby limit the movement of the handle in either direction, The ratchet-plate 2 is provided with a projection or boss 11 which is adapted to engage the cars 15 and 16, for a purpose to be hereinafter described. The fixed cam discs 26 and 27 are not in the same plane, as is indicated in Fig. 13, which is a section on the line XIIIXIII of Fig. 12, and the wing 22 of the pawl 18 is arranged to engage the edge. of cam disc 27, the boss 21 of pawl 17 being arranged to engage the edge of cam disc 26.

'Theoperationof the mechanism is as tollow-s. In the illnstratedzero or datum position, both pawls engage a tooth 4L2 that is located between the two sets of ratchetteeth 3 to 6 and 7 to 10. The movement of the handle in the clockwise direction for example, by reason of the engagement of the pawl 18 with the tooth 12, moves the ratchetplate 2 and shaft 1 a'certain distance until the head18 of the pawl, 18 comes into engagement with the first step 34 on the fixed annularplate This prevents further movement of the mechanism in the clock wise direction. The handle is now moved backwards, that is to-fsay, in the counterclockwise direction, to a certain distance, dragging the pawl 18 over the ratchet until it falls, into engagement with the tooth 7,

which it is permitted to do by reason of the cam disc 27 being-cut away at the part 13 whlch, at this time, is located opposite the win 22 of the pawl 18. ,The cam disc a 27 1S, however, shaped so as to en age the wing 22 and prevent the pawl 18 from engaging the tooth 8 of the ratchet if it is moved too far in the counter-clockwise directions v A movement ofthe handle in the clockwise direction will now rotate the ratchet plate and shaft through a furtherstep. It will be observed that, owingto the second tooth 7 of the ratchet being nearer to the axis of rotation thanthe tooth 42, the pawl 18"will escape the step 34: and can move tar enough; to engage with. the next step 35 in the annular plate 28. it further movement or the handle in the (iountcr clockwise direction will drag the pawl 18 a further dis-- tance over the ratchet," and the gap 43 in they cam 27 will permitotthe pawl to engage the third tooth 8 of the ratchet. As this tooth is still nearer to the axis of rotation, the pawl 18 will now be enabled to pass the second step 35 of the fixed plate 28 and engage thethird step 36.

During the time that the ratchetplate is being moved in the clockwise direction by means of .the pawl18, the pawl 17 v is pre vented from engaging the teeth 12 and 3 to 6 of the ratchet by reason of the engage lllellt ofthe, boss 21 with the si-loi? the fixed cam disc 26. Y

hilovement of the ratchet and shaft in the reverse direction back to the zero or datum 1 29, in a similar manner to that hereinbefore described for the movement in the clock wise direction. The cam 26 is cut away at the part 45 to enable the pawl 17 to engage the successive ratchet teeth, and the cam 27 is provided with a projecting part .46 which engages the wing 22 of the pawl 18 and pre vents it from engaging the teeth of the ratchet in a manner similar to that previously described in connection with. the boss 21 of the cam 17 and the part at of the fixed cam 26. Movement of the ratchet and shaft in the reverse direction will be obtained by engagement of theear 15with the bosstl.

The mechanism shown in the drawing is adaptedto rotate the shaft by successive steps in. either direction from the zero or datum position. It will be readily under stood, however, that the shaft may be arranged to be movedby steps in one direction only by means of a single pawl engaging appropriate ratchet teeth, in which case, one oithe fixedcams 26,27 and one of the stepped plates 28, 29 will be omitted.

The structural details of the device may be considerably varied accordingto the nature of the apparatusto which the mechanism is to be applied; for example, the steps and ratchet teeth which are shown as being formed by notches in the edges of suitably shaped plates may be replacedby properly spaced pins, and other variations maybe made without departing from the spirit and scope oi": my invention. I desire, therefore, that only such limitations shall be imposed as are indicated in the appeniled claims.

I claim as my invention: I

1. A mechanism comprising a driving member, apawl member actuated thereby, a

a notched member having a plurality o'l di lii'erentl sitinncil teeth, means for normally eilecting the engagement oil said pawl member with one of said teeth to thereby drive the notched member, and a stationary notched member having a plurality of difi'erently-positioned teeth for successively engaging said pawl member.

3. A mechanism comprising a driving rotatable member, pawl men'iber carried thereby, a rotatable ratchet member having a plurality of teeth of successively decreasing radius, means for initially effecting the engagement 0t said pawl member with the tooth 0t gratest radius, to thereby drive the ratchet member, and a stationary notched member having a plurality of teeth oit' successively varying radius for consecutively engaging said pawl member.

d. A mechanism comprising a driving rotatable member, a pawl carried thereby, a concentrically related rotatable ratchet mem her having pl irality of teeth of succes ively decreasing radius, means for initially effecting the engagement oi said pawl mem her with the tooth of greatest radius to thereby drive the ratchet member, and a station ry notched. member having a plurality of teeth of successively decreasing radius for consecutively engaging the said pawl member as the driving member is actuated alternately in opposite directions.

5. In a pawl-and-ratchet mechanism, the combination with a rotatable drying mem ber, of a pawl carried thereby, a concentrically rotatable ratchet member initially engaging said pawl to be driven thereby and having a plurality of teeth of successively decreasing radius, and stationary notched means interposed in the path of said driving member to prevent movement thereof and consequent forward rotation of the ratchet member beyond each notch of said stationary means until the pawl is bacl wardly actuated and engages a subsequent ratchet-member tooth.

6. A mechanism comprising a rotatable handle member, a pawl carried thereby, a concentrically rotatable ratchet-plate initi ally engaging said pawl to be driven thereby and having a plurality of teeth of successively decreasing radius. and a stationary aninilar notched member interposed in the path of said pawl to prevent movement thereof and consequent rotation of the ratchet-plate beyond each notch of: said notched. member until the handle member is backwardly actuated to allow the pawl to engage the next ratchet-plate tooth.

7. A mechanism comprising an oscillatory .driving member, a pawl carried thereby, a

rotatable ratchet member initially en aging said pawl to be driven thereby, and a stationary cam surface for causing said pawl to ewe-age a predetermined ratchet tooth dependent upon the position to which ratchet member has been preriously os lated.

8. A mechanism comprising a rotatable driving member, a pawl carried thereby, a rotatable ratchet member initially enp ging said pawl to be driven thereby, station notched means for preventing movement of the driving member and consequent rotation of the ratchet member beyond predetermined positions that respectively correspoml to the ratchet teeth, and a cam suriiaceflor causing said pawl to engage the next ratchet-member tooth upon a backward movement of the driving member.

9. A. mechanism comprising a rotatable handle member, a pawl carried thereby, a

concentrically rotatable ratchet-plate initially engaging said pawl to be driven thereby and having a plurality of teeth of succes'sively decreasing radius, a stationary annular notched member interposed in the path of said pawl to successively prevent movement thereof and consequent rotation ot the ratchet-plate beyond the notches of said notched member, and a cam surface tor causing said pawl to engage the next rat: retplate tooth upon preliminary backward and subsequent forward movement of the driving member.

10. A mechanism comprising a movable member, pawl members carried thereby and corresponding to opposite directions of movement, a ratchet member having a tooth engaging said pawl members to be actuated thereby in the one orthe other direction, means co-operating with said pawl members for limiting the movement of said ratchet member in a step-by-step manner in either direction, and means for rendering the initially unused pawl member inoperative during the step-by-step operation.

11. A mechanism comprising a rotatable driving member, pawls carried thereby and respectively corresponding to opposite directions of rotation, a rotatable ratchet member initially engaging said pawls to be driven thereby in the one or the other direct-ion and having two sets t teeth of successively decreasing radius, 1 cans for preventing movement of the dri ving member and consequent rotation of re ratchet member beyond predetermined positions that respectively correspond to the ratchet teeth, and means tor renderirg the initially unused pawl member inoperative during the remaining rotative movement of the ratchet member.

12. A. mechanism comprising a rotatable driving member, pawls carried thereby and 1 respectively corresponding to opposite directions of rotation, a rotatable ratchet-plate having an intermediate tooth initially engaging said pawl members to be driven thereby in the one or the other direction and "also having, on each side of said interi'nediate tooth, sets of teeth. of succes ively decreasing radius, stationary annular notched members interposed in the path of the re spective pawlsto prevent movem nt thereof and consequent rotation of the ratch t-plate in the initially'selected direction beyond the notches of the corresponding notched member, and stationary cam surfaces for causing the used aawl to en ac'e the next ratchetplate tooth upon preliminary retrogressive and subsequent progressive movement of the driving member and for rendering the initially unused pawl inoperative during the remaining rotative movement of theratchetplate. I

combination with a rotatable driving member of a aawl'carried thereb a concentrr cally rotatable ratchet member initially engaging said pawl to be driven thereby, stationary notched means interposed in the path of said driving member to prevent movement thereof and consequent forward rotation'of the ratchet memberbeyond each notch of said stationary means until the pawl is backwardly actuated and engages a subsequent ratchet-member-tooth and means on the ratchet-member to be engaged by a portion of said driving member upon a relatively long backward movement thereof to efi'ectthe return of parts to the initial positions'. i

14. A mechanism comprising" a rotatable driving member, pawls carried thereby and respectively corresponding to opposite direetions of rotationa rotatable, ratchet plate having an intermediate tooth initially engaging said pawl members to be driven thereby in the one or the other'direction and also having, on each side of said intermediate tooth, sets of teeth-oi successively dc- 13v In a paWl-and-ratchet mechanism, the

subscribed my name creasing radius, stationary annular notched members lnterposed 1n the path of the respective pawls to prevent movement thereofand consequent rotation of the ratchetplate in the initially selecteddirection' beyondthe notches of the corresponding notched mem member successively rotatable in opposite directions a member driven thereby during the motion of said driving member in one of saiddir'ections, and a plurality ofstationary stops: for'suocessively limiting the tie gree of movement of said drivlng member. 16 A mechanism comprising a driving member successively rotatable in opposite Cl1I6CtlOI1S a member driven thereby during the motion of sald driving member 111 one voi said directions, and means for successively limiting the degree of movement of said driving member in sald direction, the degree of movement in said direction being greater than the degree of movement in said other direction, whereby the position ofsaid driving member indicates the position of said driven member. v a

in testimony whereof, I have hereunto cember 1916. I

WILLIAM BRABINER- BENNITT.

this 22nd day of De- 

